Method of simultaneous measurement of two direction force and temperature using FBG sensor head

Area of Science:

• Optical Engineering
• Materials Science
• Sensor Technology

Background:

• Simultaneous measurement of physical parameters like force and temperature is crucial in various engineering applications.
• Fiber Bragg gratings (FBGs) are widely used optical sensors, but achieving simultaneous multi-parameter measurement often requires complex configurations.
• Existing methods for force and temperature sensing using FBGs can be limited by sensitivity and system complexity.

Purpose of the Study:

• To develop and present a novel method for simultaneously measuring bending force and temperature using a single sensor head.
• To investigate the use of spectral characteristics of two FBGs for indirect inference of stress and temperature.
• To enhance the sensitivity and accuracy of force measurement compared to existing FBG-based systems.

Main Methods:

• Utilizing two fiber Bragg gratings (FBGs) on a cantilever beam for indirect spectral analysis.
• Developing a sensor head with a specific geometric layout to differentiate stress distributions on the gratings.
• Analyzing the change in width of the sum of normalized transmission spectra to determine applied bending force.
• Employing a thermal chamber for controlled temperature variations during measurements.

Main Results:

• Successful simultaneous measurement of bending force (0-150 N) and temperature was achieved with a single sensor head.
• The proposed method demonstrated increased sensitivity to force, with a system sensitivity of 5.8e-3 nm/N.
• The asymmetry in spectral characteristics due to sensor head geometry was leveraged for improved force detection.

Conclusions:

• The developed sensor head offers a universal and modular approach for multi-parameter optical sensing.
• The method provides a significant improvement in sensitivity for bending force measurement using FBGs.
• This technology has potential applications in various fields requiring precise optical sensing of force and temperature.